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2.A.1.2.57
MFS-type polyamine transporter SLC18B1 or VPAT (Solute carrier family 18 member B1) of 456 aas and 12 TMSs.  Polyamines synthesized in neurons and astrocytes are stored in secretory vesicles and released upon depolarization. Vesicular storage is mediated in an ATP-dependent, reserpine-sensitive process.  SLC18B1 is the fourth member of the SLC18 transporter family, which includes vesicular monoamine transporters and a vesicular acetylcholine transporter. Proteoliposomes containing purified human SLC18B1 protein actively transport spermine and spermidine in exchange of H+. The SLC18B1 protein is predominantly expressed in the hippocampus and is associated with vesicles in astrocytes. SLC18B1 gene knockdown decreased both the amount of the SLC18B1 protein and the spermine/spermidine contents of astrocytes (Hiasa et al. 2014).  Slc18b1 knock out mice have reduced polyamine content in the brain These mice have impaired short and long term memory in novel object recognition, radial arm maze and self-administration paradigms (Fredriksson et al. 2019). Moreover, Slc18b1 KO mice have altered expression of genes involved in Long Term Potentiation, plasticity, calcium signalling and synaptic functions, and expression of components of GABA and glutamate signalling are alterred. These mutants show partial resistance to diazepam, manifested as lowered reduction in locomotion after diazepam treatment. Possibly, removal of Slc18b1 leads to reduction of polyamine contents in neurons, resulting in reduced GABA signalling due to a long-term reduction in glutamatergic signalling (Fredriksson et al. 2019).

Accession Number:Q6NT16
Protein Name:MFS-type transporter SLC18B1
Length:456
Molecular Weight:48869.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:12
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate Unknown, NONE

Cross database links:

Entrez Gene ID: 116843   
Pfam: PF07690   
KEGG: hsa:116843   

Gene Ontology

GO:0016021 C:integral to membrane
GO:0055085 P:transmembrane transport

References (3)

[1] “Complete sequencing and characterization of 21,243 full-length human cDNAs.”  Ota T.et.al.   14702039
[2] “The DNA sequence and analysis of human chromosome 6.”  Mungall A.J.et.al.   14574404
[3] “The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).”  The MGC Project Teamet.al.   15489334

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MEALGDLEGP RAPGGDDPAG SAGETPGWLS REQVFVLISA ASVNLGSMMC YSILGPFFPK 
61:	EAEKKGASNT IIGMIFGCFA LFELLASLVF GNYLVHIGAK FMFVAGMFVS GGVTILFGVL 
121:	DRVPDGPVFI AMCFLVRVMD AVSFAAAMTA SSSILAKAFP NNVATVLGSL ETFSGLGLIL 
181:	GPPVGGFLYQ SFGYEVPFIV LGCVVLLMVP LNMYILPNYE SDPGEHSFWK LIALPKVGLI 
241:	AFVINSLSSC FGFLDPTLSL FVLEKFNLPA GYVGLVFLGM ALSYAISSPL FGLLSDKRPP 
301:	LRKWLLVFGN LITAGCYMLL GPVPILHIKS QLWLLVLILV VSGLSAGMSI IPTFPEILSC 
361:	AHENGFEEGL STLGLVSGLF SAMWSIGAFM GPTLGGFLYE KIGFEWAAAI QGLWALISGL 
421:	AMGLFYLLEY SRRKRSKSQN ILSTEEERTT LLPNET